Hello Marco,
Off the top of my head the following comes to mind:
Real-time systems "assume" a controlled environment. When you use the network,
the network card starts firing off interrupts and the system, real-time or not,
has to handle those. Now, in a real-life case, you would have planned exactly
what type of load these interrupts can have on your system and would have planned
the task scheduling and hardware structure accordingly. This isn't the case
right now as you have a "user" involved ... and that's lots of underterministic
behavior in most books ;)
I might be off a little, but I think this is part of your answer ...
Best regards
Karim
[EMAIL PROTECTED] wrote:
>
> Hello everybody,
>
> my Realtime application is now in a state where I can say it is working,
> and its working very well so far :)
>
> What I noticed during my tests is that sometimes my realtime tasks takes
> very different times to complete, with a minimum of about 110 microseconds
> and a maximum of about 350 microseconds.
>
> This task is running at 1kHz, reading and writing 2x16 bits of IO from 2
> DIO-Boards
> and then executing some functions. The problem is, its is doing EXCACTLY the
>
> same things as long as the IO-signals dont change ... so theoretically it
> should
> always have the same execution time ......
>
> There is no other RT Task which could interrupt it, and no interrupts are
> used in
> my module.
>
> I'm runnning my app on a diskless station, 500MHz Celeron, 128 MB RAM, Intel
> EEPro,
> RTAI 1.4 with Kernel 2.2.16. XWindows is running at 1024x768, and I am also
> connected
> with an X-Terminal on Windows NT.
>
> So my question is: what could influence my Realtime task so that its
> execution time differs
> from time to time ? I noticed execution time going up when I have X running
> and when
> I am running applications from my X-Server on NT.
>
> Any ideas anybody (and maybe a solution :) ?
>
> Thanks in advance,
>
> Marco Schwarz.
>
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--
===================================================
Karim Yaghmour
[EMAIL PROTECTED]
Operating System Consultant
(Linux kernel, real-time and distributed systems)
===================================================
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